We propose a 5-year renewal of the on-going Program Project Grant "An Interdisciplinary Program in Biomaterials Science". The Project continues its orignial goal, "an understanding of natural biological materials and synthetic substitutes considered in the context of both fundamental mechanism and modes of unction in complex corporeal and extra-corporeal systems." The 15 projects proposed represent either (1) continuations of on-going research, (2) new syntheses arising out of interactions between project investigators over the past 4 years, or (3) entirely new efforts. All projects fall within one or more subgoals: (1) basic research into ineractons of blood components with both synthetic materials and natural polymers, (2) synthesis and preparation of a variety of bio-compatible materials suitable for specific uses in medicine, (3) development and improvement of methods for the physicochemical and biological evaluation and characterization of biomaterials, and/or (4) implementation of studies to improve organ preservation and procurement. These PPG goals are shown to be congruent with the action plans of the NHLI as expressed in its first annual report to the Congress. The interdisciplinary breadth of the program, both within projects and between projects, is demonstrated by the 24 poject investigators, educated and experiened in the physical, biological, and engineering sciences, and in medicine. The recruitment of such a diverse but interrelate group involved the participation of individuals from the Massachusetts Institute of Technology, Harvard University, Boston University, Northeastern University, Massachusetts General Hospital, Peter Bent Brigham Hospital, Beth Israel Hospital, andthe Childrens Hosital Medical Center, representing, collaboratively, a consolidated research community in the Cambridge-Boston area. In discussion ofthe current status of the program, the most significant scientific accomplishments are briefly enumerated; full references are given for the 410 publications produced by the 4 years of effort to date. The local scientific review of the PPG has resulted in reduced funding of certain projects, with the reallocation of obligated funds to more promising and productive investigations, including the initiation of new relevant lines of inquiry.